Wireless communication systems are widely used to provide voice and data services for multiple users using a variety of access terminals such as cellular telephones, laptop computers and various multimedia devices. Such communications systems can encompass local area networks, cellular telephone and/or mobile broadband networks. The communication system can use one or more multiple access techniques, such as Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Code Division Multiple Access (CDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA) and others. Mobile broadband networks can conform to a number of system types or partnerships such as, General Packet Radio Service (GPRS), Worldwide Interoperability for Microwave Access (WiMAX), Universal Mobile Telecommunications System (UMTS), the 3rd Generation Partnership Project (3GPP), 1X Evolution-Data Optimized EV-DO, or Long Term Evolution (LTE). The LTE radio access technology is based on 3GPP Release 8 (Rel-8). The 3GPP Release 10 (Rel-10) standard, also known as, Long Term Evolution Advanced (LTE-A), further extends the performance and capabilities of the LTE radio access technology. The LTE and LTE-A encompass the evolution of the radio access network through the E-UTRAN (Evolved Universal Terrestrial Radio Access Network).
Relay nodes (RNs) are being standardized for Rel-10 and play a significant role in the LTE-A. RNs can increase coverage and cell edge throughput, and provide group mobility or temporary network deployment. A RN is wirelessly connected to a donor cell, also referred to as a donor enhanced Node B (eNB or D-eNB), or a base station. The RN may serve as an eNB to one or more User Equipment (UE), or mobile stations, terminals, users, and so forth. The link between a RN and a UE is referred to as an access link or a Uu link, while the link between an eNB and a RN is referred to as a backhaul link or a Un link. To a UE that is being served by a RN, the RN may appear identical to an eNB, with the RN scheduling uplink (UL) and downlink (DL) transmissions to the UE over an access link.
Multicast-Broadcast Single Frequency Network (MBSFN) operation involves simultaneous transmission of the same waveform from multiple cells over a single frequency. MBSFN subframes which were first defined in LTE initially intended for broadcast support. However, given that the control and pilot overhead is lower than on a normal subframe and using MBSFN subframe can keep the backward compatibility with legacy UE, it was later decided that MBSFN subframes may be used by any device, including RN. In particular, it was decided that for RNs, the backhaul link (between the eNB and the RN, also known as Un link) data would be carried on subframes configured as MBSFN subframes in the relay cell. From eNB frame aspect, the Un subframe can be normal subframe or MBSFN subframe which can be left to the implementation. For RN frame aspect, the Un subframe is always configured as MBSFN subframe. The definition of the MBSFN subframe pattern is included in the System Information Block Type 2 (Specified in 3GPP document 36.331, “Radio Resource Control (RRC) Protocol Specification”). The MBSFN subframe pattern can be defined with either a 10-subframe (10 ms) periodicity, or a 40-subframe (40 ms) periodicity.